The primary functions of the Human Subjects Core are as follows. (1) Recruitment of human subjects from majority and minority populations for participation in the longitudinal study of age-related hearing loss and in experiments proposed in each project. (2) Collection, storage, and analysis of demographic, audiologic, and biologic/medical data and tissue (blood and DMA) from human subjects enrolling in and continuing in the longitudinal study. These data define the basic demographic, audiologic, and medical profiles of each subject and are organized into searchable databases, which provide key information needed by investigators in each project to select subjects according to the needs of their experiments. (3) Coordination of subject schedules for the audiologic and medical test battery, annual evaluations, longitudinal measures, and visits to the Otolaryngology clinic and to the General Clinical Research Center (GCRC). Because of the strong links among projects, there is substantial overlap of needs for subject participation across projects. Thus, a major function of the Human Subjects Core is to make efficient use of subjects' testing time.